CRM-12233 Add upgrade statement to fix Membership field label for quick config

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* CRM-12233: Online membership signup - contribution amounts field should not be required + various notices
  http://issues.civicrm.org/jira/browse/CRM-12233
Merge pull request #281 from davecivicrm/CRM-12233

CRM-12233 Add upgrade statement to fix Membership field label for quick ...